Polyester copolymer

ABSTRACT

Disclosed is a polyester copolymer obtained by reacting (A) a dicarboxylic acid component composed mainly of terephthalic acid or its derivative with (B) a glycol component comprising 15 to 85 mole % of (B-1) an aliphatic diol having 2 to 16 carbon atoms and 85 to 15 mole % of (B-2), 1,4-cyclohexanedimethanol in which the content of the trans-form is at least 80 mole %. This polyester copolymer has a low rate of crystallization and provides a shaped article having a high heat resistance.

DESCRIPTION

1. Technical Field

The present invention relates to a polyester copolymer which gives ashaped article having a high heat resistance and which has a low rate ofcrystallization.

2. Background Art

Polycyclohexylenedimethylene terephthalate obtained from terephthalicacid and 1,4-cyclohexanedimethanol has a high melting point, andtherefore, this polyester has a high heat resistance and a highresistance against the hydrolysis.

Attempts have been made to use this polyester as films or bottles byutilizing this characteristic property. This polyester, however,involves a problem in that since the polyester is readily crystallized,the range of the shaping conditions is narrow.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a polyester copolymerhaving a low rate of crystallization and providing a shaped articlehaving a high heat resistance.

More specifically, in accordance with the present invention, there isprovided a polyester copolymer obtained by reacting (A) a dicarboxylicacid component composed mainly of terephthalic acid or a derivativethereof with (B) a glycol component comprising (B-1) 15 to 85 mole % ofan aliphatic diol having 2 to 16 carbon atoms and (B-2) 85 to 15 mole %of 1,4-cyclohexanedimethanol in which the trans-form content is at least80 mole %.

BEST MODE FOR CARRYING OUT THE INVENTION

The dicarboxylic acid component (A) used in the present inventionpreferably comprises at least 90 mole % of terephthalic acid or aderivative thereof. As the terephthalic acid derivative, there can bementioned dialkyl esters of terephthalic acid having 1 to 10 carbonatoms in the alkyl group and diaryl esters of terephthalic acid having 6to 14 carbon atoms in the aryl group. As specific examples of theterephthalic acid derivative, there can be mentioned dimethylterephthalate, diethyl terephthalate, dipropyl terephthalate, dibutylterephthalate and diphenyl terephthalate.

As the other dicarboxylic acid that can be used together withterephthalic acid or its derivative in an amount of not more than 10mole % of the dicarboxylic acid component, there can be mentionedphthalic acid, isophthalic acid, adipic acid, sebacic acid,naphthalene-1,4-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid.

The glycol component (B) used in the present invention comprises (B-1)15 to 85 mole % of an aliphatic diol having 2 to 16 carbon atoms and(B-2) 85 to 15 mole % of 1,4-cyclohexanedimethanol in which the contentof the trans-form is at least 80 mole %.

As the aliphatic diol (B-1) having 2 to 16 carbon atoms, there can bementioned ethylene glycol, propylene glycol, tetramethylene glycol,hexamethylene glycol, neopentyl glycol, octamethylene glycol, butylethylpropanediol, diethyl propanediol and3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane,and ethylene glycol, propylene glycol, tetramethylene glycol andhexamethylene glycol are especially preferably used. These aliphaticdiols can be used alone or in the form of a mixture of two or morethereof. A polyester copolymer obtained by using an aliphatic diolhaving more than 16 carbon atoms as the aliphatic diol is not preferredbecause a shaped article obtained from this copolymer has not asatisfactory heat resistance.

The amount of the aliphatic diol (B-1) having 2 to 16 carbon atoms is 15to 85 mole %, preferably 30 to 70 mole %, based on the glycol component(B). The polyester copolymer in which the content of the component (B-1)is less than 15 mole % based on the component (B) cannot be used forattaining the object of the present invention, because the rate ofcrystallization of the polyester copolymer is high. The polyestercopolymer in which the content of the component (B-1) is higher than 85mole % based on the component (B) is not preferably used, because therate of crystallization becomes high or the glass transition temperatureis too low.

The content of the trans-form in 1,4-cyclohexanedimethanol (B-2) used inthe present invention must be at least 80 mole %. A shaped articleformed from a polyester copolymer obtained by using1,4-cyclohexanedimethanol having a trans-form content less than 80 mole% is not satisfactory in the heat resistance.

The polyester copolymer of the present invention can be obtained byusing terephthalic acid, dimethyl terephthalate or other terephthalicacid derivative, and ethylene glycol or other aliphatic diol and1,4-cyclohexanedimethanol composed mainly of the trans-form as the mainstarting materials, carrying out an esterification reaction or an esterexchange reaction and subsequently, conducting a polycondensationreaction.

Catalysts customarily used for the preparation of polyesters can be usedfor the esterification reaction or ester exchange reaction and thepolycondensation reaction.

A flame retardant, a fibrous reinforcer, a filler, an oxidationstabilizer, a heat stabilizer, a colorant, an ultraviolet absorbent andthe like can be added to the polyester copolymer of the presentinvention according to need.

The present invention will now be described with reference to thefollowing examples.

EXAMPLES 1 THROUGH 9 AND COMPARATIVE EXAMPLES 1 THROUGH 4

Terephthalic acid as the dicarboxylic acid component and a glycolcomponent comprising 1,4-cyclohexanedimethanol, ethylene glycol,1,4-butanediol and 1,6-hexanediol at a ratio shown in Table 1 weresubjected to esterification at 260° C. in the presence of tetrabutyltitanate as the esterification catalyst in an amount of 0.1% based onthe obtained polymer. Then antimony trioxide and phosphorous acid wereadded as the polycondensation catalyst in amounts of 0.03% and 0.04%,respectively, and polycondensation was carried out under a reducedpressure at 285° to 320° C., whereby various polyester copolymers wereprepared. Each of the obtained polyester copolymers was recovered in theform of a strand polymer, cooled with water and pelletized by a cutter.

Each of the obtained polyester copolymers was decomposed with an aqueoussolution of hydrazine, and the glycol component was analyzed by the gaschromatography. The results are shown in Table 1.

Each of the obtained polyester copolymers was dissolved in aphenol/tetrachloroethane mixed solvent (1/1 weight ratio) and theintrinsic viscosity ηsp/C was measured at a polymer concentration of 0.5g/dl. The results are shown in Table 1.

The obtained pellet was molded into a molded article having a thicknessof 6.4 mm, a length of 127 mm, and a width of 12.6 mm by using a 1-ouncesmall injection molding machine at a cylinder temperature of 310° to320° C. and a mold temperature of 310° to 320° C.

Each of the molded articles was a transparent test piece. Each testpiece was heated at 140° C. corresponding to the molding temperature forthe preparation of a sheet or a bottle for 15 minutes, and the degree ofwhitening by the crystallization was examined. The results are shown inTable 1.

The degree of whitening was evaluated according to the following scale:

A: transparent (not changed)

B: slightly whitened and hazy

C: frosted glass-like and trasparent

D: turbid and opaque

                                      TABLE 1                                     __________________________________________________________________________             Trans-form                                                                          Composition of    Whitening                                             content                                                                             glycol component  degree                                                (mole %)                                                                            (mole %)          after                                                 of CHDM                                                                             CHDM EG BG HG η.sub.sp /C                                                                   heating                                      __________________________________________________________________________    Example                                                                              1 90    80   20 -- -- 0.74                                                                              B                                            "      2 90    70   30 -- -- 0.77                                                                              A                                            "      3 90    50   50 -- -- 0.76                                                                              A                                            "      4 90    30   70 -- -- 0.79                                                                              A                                            "      5 90    20   80 -- -- 0.73                                                                              B                                            "      6 95    70   30 -- -- 0.73                                                                              A                                            "      7 83    70   30 -- -- 0.76                                                                              B                                            "      8 90    70   -- 30 -- 0.75                                                                              A                                            "      9 90    70   -- -- 30 0.73                                                                              A                                            Comparative                                                                          1 90    100  -- -- -- 0.78                                                                              D                                            Example                                                                       Comparative                                                                          2 90    --   100                                                                              -- -- 0.72                                                                              D                                            Example                                                                       Comparative                                                                          3 70    80   20 -- -- 0.74                                                                              C                                            Example                                                                       Comparative                                                                          4 70    70   30 -- -- 0.71                                                                              C                                            Example                                                                       __________________________________________________________________________     Note                                                                          CHDM: 1,4cyclohexanedimethanol                                                EG: ethylene glycol                                                           BG: 1,4butanediol                                                             HG: 1,6hexanediol-                                                       

INDUSTRIAL APPLICABILITY

The polyester copolymer of the present invention has a low rate ofcrystallization, and a shaped article obtained from this copolymer has ahigh heat resistance. Accordingly, the range of application of theshaped article of the polyester resin is wider.

We claim:
 1. A polyester copolymer obtained by reacting (A) adicarboxylic acid component composed mainly of terephthalic acid or aderivative thereof with (B) a glycol component comprising (B-1) 15 to 85mole % of an aliphatic diol having 2 to 16 carbon atoms and (B-2) 85 to15 mole % of 1,4-cyclohexanedimethanol in which the trans-form contentis at least 80 mole %.
 2. A polyester copolymer as set forth in claim 1,wherein the derivative of terephthalic acid is a dialkyl ester ofterephthalic acid having 1 to 10 carbon atoms in the alkyl group or adiaryl ester of terephthalic acid having 6 to 14 carbon atoms in thearyl group.
 3. A polyester copolymer as set forth in claim 1, whereinthe glycol component (B) comprises 30 to 70 mole % of the aliphatic diol(B-1) and 70 to 30 mole % of 1,4-cyclohexanedimethanol (B-2).
 4. Apolyester copolymer as set forth in claim 1, wherein the aliphatic diolis ethylene glycol.
 5. A polyester copolymer as set forth in claim 1,wherein the aliphatic diol is at least one member selected from thegroup consisting of propylene glycol, tetramethylene glycol andhexamethylene glycol.